Preparation of 1-alkylimidazoles

Abstract

Process for the preparation of 1-alkylimidazoles of the general formula (I) ##STR1## where R 1 is alkyl, R 2 and R 3 are hydrogen, alkyl, aryl, arylalkyl, or alkylaryl, R 4 is carboxy, alkoxycarbonyl R 5 OCC--, carbamoyl, or cyano, and R 5 is an alkyl of from 1 to 8 carbon atoms--by the reaction of imidazoles of the general formula (II) ##STR2## with dialkyl sulfates of the general formula (III) (R.sup.1 O).sub.2 SO.sub.2 (III) at elevated temperatures in the presence of a carboxylic acid or anhydride or of both acid and anhydride.

We claim: 
     
       1. A process for preparation of a 1-alkylimidazole of the formula (I) ##STR6## wherein R 1  is alkyl, R 2  and R 3  are hydrogen, alkyl, aryl, arylalkyl, or alkylaryl, R 4  is carboxy, alkoxycarbonyl R 5  OOC--, carbamoyl, or cyano, and R 5  is an alkyl of from 1 to 8 carbon atoms by the reaction of an imidazole of the formula (II) ##STR7## with a dialkyl sulfate of the formula (III)   (R.sup.1 O).sub.2 SO.sub.2                                 (III)     at elevated temperatures in the presence of a carboxylic acid or anhydride or of both acid and anhydride.   
     
     
       2. A process as claimed in claim 1 wherein the reaction is carried out in an aliphatic carboxylic acid of from 1 to 8 carbon atoms, or an aliphatic carboxylic anhydride of from 4 to 16 carbon atoms, or a mixture of both. 
     
     
       3. A process as claimed in claim 1 wherein the reaction is carried out in an aliphatic carboxylic anhydride of from 4 to 12 carbon atoms. 
     
     
       4. A process as claimed in claim1 wherein the reaction is carried out in the presence of from 40 ml to 2000 ml of a carboxylic acid or anhydride or of both acid and anhydride per mole of the imidazole (II).